Pump actuator and method for pump operation

ABSTRACT

Method and apparatus for controlling a moveable pumping diaphragm and a liquid color diaphragm pump, including a housing, a movable pin slidably residing within the housing, a potentiometer connected to and residing within the housing for sensing movement of the pin, riding against the diaphragm of the pump and a spring for biasing the pin against the diaphragm.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 13/913,375 filed 7 Jun. 2013 in the name of StephenB. Maguire and published as U.S. 2013/0334258 A1, the priority of whichis claimed under 35 USC 120. The '375 application claims the benefit ofthe priority under 35 USC 119 and 35 USC 120 of provisional U.S. patentapplication Ser. No. 61/660,326 filed 15 Jun. 2012 in the name ofStephen B. Maguire and entitled “Molded Diaphragm Pump.” The instantapplication similarly claims the benefit of the priority of the '326application through the parent '375 application noted above. Thedisclosures of both of these preceding applications are herebyincorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to pumps and more specifically to diaphragm andpiston pumps used to pump liquid color. The patent application even morespecifically pertains to a device used to actuate the pumping action ofa liquid color diaphragm pump. The liquid color diaphragm pump ispreferably, but not necessarily, a liquid color pump installed on thelid of a liquid color container. Most preferably the liquid color pumpis an integral part of the lid of a drum of liquid color container.

2. Description of the Prior Art

Diaphragm pumps and piston pumps are known. In both diaphragm pumps andpiston pumps, the pump provides a reciprocating action whereby the pumpalternately displaces liquid and then pulls in additional liquid to bepumped from a pumping chamber. All such pumps involved two check valves.An inlet check valve allows liquid to enter the pumping chamber, butprevents liquid from exiting back out of the pumping chamber through theinlet check valve. An outlet check valve allows the pumped liquid toexit the pumping chamber and prevents the liquid from returning to thepumping chamber through the outlet check valve.

In a diaphragm pump, the moving diaphragm serves to suck liquid throughthe inlet into the pumping chamber and then pumps the liquid by applyingpressure to the liquid to force the liquid out of the pumping chambervia the liquid outlet.

SUMMARY OF THE INVENTION

In one of its aspects, this invention provides a method for operating apump having a moveable pumping member within a pumping chamber, wherethe method preferably includes positioning a moveable reciprocablemember in contact with a pumping member to move reciprocally in concertwith the pumping member. In this aspect, the invention preferablyproceeds with sensing position of the reciprocable member, which isindicative of the position of the pumping member, and producing a signalindicative thereof. The method then preferably proceeds in this aspectby periodically applying force to the pumping member to move the pumpingmember and thereby effectuate pumping of liquid from the chamber. Themethod preferably further involves using the signals to regulatefrequency of force application to the pumping member to achieve apreselected rate of output from the pump.

In one application of the actuator of the invention, addition of colorto a plastic molding or processing operation requires careful metering,which this invention provides. When such color is added, the rate ofcolor dispensing must exactly match the rate requirement of the processmachine. Consequently, speed of the liquid color pumping process must becarefully controlled. In the instant invention, rate of pumping iscontrolled and even partial pumping strokes may be effectuated by theinvention preferably pulsing very small bursts of air into the liquidcolor pump above the diaphragm portion of the pump. By regulating theduration of each air pulse and regulating the time between air pulses,the invention facilitates metering liquid color at a desired preciselycontrolled flow rate.

The actuator of the invention preferably provides continuous feedback ofthe exact position of a liquid color pump diaphragm at all times as airpushes the diaphragm downward during the pumping stroke. Such continuousfeedback information regarding the exact position of the diaphragm atall times preferably allows continuous monitoring and correction ofliquid color flow rate by regulation of the frequency and duration ofthe air pulses applied to the diaphragm and also preferably facilitatesaccurate, partial strokes of the pumping diaphragm. The inventionaccomplishes this by preferably providing a moveable pin that followsthe diaphragm of the liquid color pump as the diaphragm moves down andup. The invention further accomplishes this by using a linearpotentiometer in a position so that the potentiometer is within theactuator and senses movement of the pin.

In a typical application, total movement of the diaphragm portion of theliquid color pump is preferably about one-quarter of one inch. Thepreferred slide potentiometer portion of the actuator of the inventionis preferably capable of about 20 millimeters, or about three-quartersof an inch, of movement of the sensing slide of the potentiometer. Inthe course of practice of the invention, the upper and lower limits ofpotentiometer movement are preferably recorded using a microprocessorand readings in between these upper and lower limits are preferably usedto calibrate the actuator to determine the precise location of the pinand hence of the diaphragm as the diaphragm moves up and down and pumpsthe liquid color.

In the most preferred operation of the invention, the invention utilizesonly about one-quarter inch of the diaphragm movement, which translatesinto about 300 different position readings of the moveable potentiometerarm, and hence the position of the pin riding the diaphragm, and theposition of the diaphragm itself, thereby assuring precise locationinformation at all times respecting the position of the pumpingdiaphragm.

In the preferred manifestation of the invention, the potentiometerpreferably is entirely within a chamber interior of the actuator, whichchamber is pressurized. Electrical signals from the potentiometer arebrought out of the actuator and out of the pressurized chamber withinthe actuator preferably via screws that make contact with thepotentiometer connections inside the actuator that are themselves sealedagainst air leakage where they enter the actuator body. The absence ofany moving, sliding seals assures correct operation of the potentiometerand actuator for many years with there being no wear points to fail.

A light spring, above the slide arm of the potentiometer and biasing theactuator pin downwardly, assures that the potentiometer slide arm or“T-bar” and the actuator pin follow the diaphragm downwardly as airpushes the diaphragm down.

The actuator is removable from the pump using a one-quarter turn lockingsystem with an O-ring base. This allows the actuator to be installed orremoved easily and frequently, while effectively sealing the actuatoragainst the pump surface whenever the actuator is installed.

The method aspect of the invention may preferably further includerecording signals at the extremities of actuator pin travel, using thosesignals and the known length of actuator pin travel to determinelocation of the actuator pin based on signal received at a given timeand adjusting the frequency of application of force to the pumpingdiaphragm according to the location of the actuator pin and thepotentiometer slide arm or T-bar, to maintain the desired output fromthe pump.

The method may further involve using the signals and known length of theactuator pin travel to determine location of the actuator pin based onsignal received at a given time and may further include determining therelationship between the duration of force application to the pumpingdiaphragm and the pumping diaphragm displacement.

In another one of its aspects, this invention provide apparatus forcontrolling a moveable pumping member and a pump, where the apparatusincludes a housing, a reciprocally moveable pin slidably residing withinthe housing, and having an extremity portion passing through the housingfor contacting the moveable pumping diaphragm and moving unitarily withthe moving pumping diaphragm. The apparatus aspect of the inventionfurther preferably includes a potentiometer connected to and residingwithin the housing for sensing movement of the pin and producing asignal indicative thereof, and spring for biasing the pin against thepumping member. A microprocessor is also included, as is a solenoidvalve, for regulating air bursts applied to the diaphragm to facilitatepumping.

In the apparatus aspect of the invention, the housing may have a firstaperture for connection to a supply of pulsed air, where the housing isotherwise sealed and air tight except optimally for passage of air alongthe pin where the pin passes through the housing.

In the apparatus aspect of the invention, the potentiometer desirablyhas a moveable slide arm or T-bar portion positioned between andcontacting both the light upper spring and the pin. In the apparatusaspect of the invention, the actuator housing is preferably at leastpartially polymer foam. In the apparatus aspect of the invention, thesignals are desirably electrical signals and the potentiometer desirablyhas terminals providing the electrical signals indicative of movement ofthe pin. In such aspect of the invention, the apparatus furthercomprises signal carriers electrically connected to terminals in passingthrough the housing, and electrical connectors mounted on the housingexterior and being electrically connected to the signal carriers, forconnection to the microprocessor, to in turn activate the solenoid valveto apply bursts of pumping air to the diaphragm. In the apparatus aspectof the invention, the pumping member is desirably a diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation of an actuator embodying aspects of theinvention.

FIG. 2 is a left side elevation of the actuator illustrated in FIG. 1.

FIG. 3 is a right side elevation of the right side actuator illustratedin FIGS. 1 and 2.

FIG. 4 is an isometric view of the actuator illustrated in FIGS. 1through 3 showing the bottom of the actuator and the left quarter of theactuator, namely the side portion of the actuator shown partially inFIG. 1 and partially in FIG. 2.

FIG. 5 is an isometric view of the actuator illustrated in FIGS. 1through 4 showing the right quarter of the actuator, namely the sideportion of the actuator illustrated in FIGS. 1 and partially in FIG. 3.

FIG. 6 is an isometric view of the actuator showing the top of theactuator and the front left quarter side portion illustrated in FIG. 4.

FIG. 7 is an isometric view of the actuator showing the top of theactuator and the front right quarter side portion illustrated in FIG. 5.

FIG. 8 is a top view of the actuator illustrated in FIGS. 1 through 7.

FIG. 9 is a sectional view of the actuator illustrated in FIGS. 1through 8, with the section taken at lines and arrows A-A in FIG. 8.

FIG. 10 is a sectional view of the actuator illustrated in FIGS. 1through 9, with the section taken at lines and arrows B-B in FIG. 8.

FIG. 11 is a schematic view, partially in section, showing the actuatorillustrated in FIGS. 1 through 10 together with a connectedmicroprocessor and a connected solenoid valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS AND BEST MODE KNOWN FORPRACTICE OF THE INVENTION

The actuator 43 of this invention has specific applicably to liquidcolor diaphragm pumps; the actuator may also be used with piston-typepumps.

In a pump to which the actuator is best adapted for use, such as thatdisclosed in pending U.S. Ser. No. 13/913,375, air is applied to the topside of the diaphragm, to press the diaphragm down. This downwardmovement of the diaphragm defines the “pumping stoke”. In the pump, aspring on the bottom side of the diaphragm acts against the diaphragm tomove the diaphragm up. Upward movement of the diaphragm in response tothe spring pressure defines the “suction stroke”.

In the preferred pump, normally the diaphragm is operated in fullstrokes, moving through the full range of motion for which the diaphragmis designed in the pump. Moving the diaphragm downward through the fullrange of motion is preferably accomplished by opening a solenoidactuated air valve 70 and applying air pressure to move the diaphragmpreferably all the way to the bottom of its range of motion, which maybe to the bottom of the pumping cavity.

When liquid color is used to color plastic parts during fabrication,careful metering of liquid color consumption is required as the liquidcolor is added while the plastic resin is melted and processed by aprocess machine. The rate the liquid color is dispensed by the pump mustexactly match the rate at which the liquid color is consumed by theprocess machine.

The rate or speed of the liquid color pumping process must be preciselycontrolled. In some applications only require partial pump strokes arerequired. The rate at which liquid color is supplied by the pump iscontrolled by carefully pulsing only very small bursts of air into thepump, into the space above the diaphragm. Regulating the duration ofeach air pulse and regulating the time between pulses results inmetering the liquid color to the process machine at exactly the desiredflow rate so that the process machine receives precisely the amount ofliquid color the process requires, at exactly the right rate of supplyof liquid color.

Critical to the success of this process for supplying liquid color ishaving continuous feedback of the exact position of the diaphragm at alltimes as compressed air released by solenoid valve 70 pushes thediaphragm downward. Knowing the exact position of the diaphragm at alltimes allows accurate continuous monitoring and correction of the liquidcolor flow rate by regulation of the solenoid valve by the potentiometerand microprocessor, and also allows accurate metering of partial stokesof the diaphragm.

The actuator of this invention accomplishes this by providing a pin 42that lightly rides the surface of the diaphragm, following the diaphragmas the diaphragm moves down and up. The actuator 43 of this inventionfurther involves positioning a potentiometer 36, most desirably a linearpotentiometer, so that potentiometer 36 is actuated by movement of pin42. In one preferred embodiment, total diaphragm movement in theinvention may be about 0.25 inch. The potentiometer arm 40 and pin 42may move about 0.75 inch or more, but in the preferred embodiment, theinvention typically uses only 0.25 inch of that stroke.

Initially, a microprocessor 68 records the upper and lower extremepositions of the linear potentiometer slider arm 40, corresponding tothe upper and lower limits of diaphragm travel. The microprocessor 68then uses the readings of the potentiometer slider arm 40 that arebetween the corresponding upper and lower limits of diaphragm travel todetermine the exact location of the diaphragm as the diaphragm moves upand down and pumps liquid color. The 0.25 inch of stroke of thediaphragm translates into about 300 different position readings of thepin 42 and potentiometer slider arm 40, which may be stored and used bythe microprocessor, assuring precise readout of diaphragm location atany time.

The invention provides pin 42 for physical connection of potentiometer36 with the top side of a diaphragm. This is to sense the movement ofthe diaphragm. Using a moving pin passing through an air pressure sealwould risk leaking air around the seal. Any such air leak, even theslightest air leak, would compromise metering accuracy.

The invention has no parts moving through a seal. The potentiometer andpin are enclosed entirely within an actuator internal chamber 274 thatis pressurized.

Electrical signals from the potentiometer are brought out of thepressurized volume of actuator internal chamber 274 through screws 257making contact with potentiometer electrical leads 268, which in turnconnect with the potentiometer electrical leads 270 inside thepressurized volume; the screws themselves are sealed against air leakagewhere they enter the pressurized chamber. Absence of any moving orsliding seals assures correct operation for many years with no wearpoints to fail.

A light spring 38, above slide portion 40 of potentiometer 36 andbearing on pin 42, assures that pin 42 follows the diaphragm down as theair pushes the diaphragm down. Preferably a heavy pump spring, inside apreferred pump, pushes the diaphragm up at the end of a pump stoke, andthe diaphragm then pushes pin 42 and potentiometer slide portion 40 upagainst the bias of light spring 38.

The actuator 43 is removable from the pump. Preferably a one-quarterturn locking system with an O-ring base seal allows the actuator to beinstalled or removed easily while effectively sealing against the pumpsurface.

In the drawings it can be seen that that actuator 43 is generallycylindrical in form, with an air inlet 44 at the top thereof being fedby an air supply line 45, which supplies air indirectly with the airbeing controlled by solenoid valve 70 preferably operating off of ahouse air line 74. A microprocessor 68 receives signals from the slidepotentiometer designated generally 36 which is resident within actuator43. Also resident within actuator 43 is light biasing spring 38 whichworks to bias actuator pin 42 and intervening T-bar portion 40 of slidepotentiometer 36 downwardly. This downward bias of actuator pin 42assures that the end of actuator pin 42 is always riding on thediaphragm of a pump being controlled by actuator 40.

The diaphragm of the pump does the actual pumping. Spring 38, slidepotentiometer 36 and actuator pin 42 monitor the position of thediaphragm in the pumping chamber as the diaphragm moves in response toair pressure, most desirably bursts of air pressure, applied to the topside of the diaphragm as air passes downwardly around the edges ofactuator pin 42, as the air is released by intermittent operation ofsolenoid valve 70 when triggered by microprocessor 68. The air maintainsa pressurized condition within actuator internal chamber 274.

Actuator 43 has an upper portion 250 and a lower portion 252 which areconnected and held together by hold down bolts 256. An actuator internalgasket 254 resides between actuator upper portion 250 and actuator lowerportion 252.

Actuator upper portion 250, within which actuator chamber 274 islocated, is preferably insulative, air tight polymer foam.

Actuator 43 further includes actuator signal connection externalterminals designated 258 in the drawings which have associated therewithtubular connection covers 260, so that suitable wire connections can bemade to actuator signal connection external terminals 258, with the wireconnections desirably passing through tubular connection covers 260.

Actuator 43 further includes a pair of lugs 262 which form the malepotion of a preferable quarter turn quick disconnect assembly whichallows actuator 43 to be quickly removed from the liquid color pump andreplaced if need be. A handle 264 is provided as part of actuator 43 toassist in manual, preferably quarter turn, rotational movement ofactuator 43 to remove it from the liquid color pump.

An abutment plug is provided at the top of pin biasing spring 38, asillustrated in FIG. 11, with a tiny passageway optionally being providedthrough abutment plug 266 to facilitate air passage from the solenoidvalve downwardly through actuator 43 into contact with the upper serviceof a diaphragm portion of a liquid color pump to which actuator 43 isconnected. Alternatively, air from solenoid valve 70 may pass around thesides of a solid abutment plug 266, between abutment plug 266 and theannular interior surface of actuator upper portion 250, to reach thepumping diaphragm.

Electrical leads from slide potentiometer 36 that are internal toactuator 43 are designated generally 268. These leads extend frompotentiometer electrical terminals 270 that are shown in FIG. 11. Anactuator chamber 274 is present within upper portion 250 of actuator 43with slide potentiometer 36, pin biasing spring 38, and the upperportion of actuator pin 42 all being resident therewithin, asillustrated in FIGS. 10 and 11. The actuator chamber 274 present withinupper portion 250 of actuator 43 houses slide potentiometer 36, pinbiasing spring 38 and the upper portion of actuator pin 42. Uponmicroprocessor 68 actuating solenoid valve 70 to provide a pulse of airvia air inlet 44, the air passes downwardly through inlet 44 intoactuator chamber 274 and around and between pin 42 and the surroundinglower portion 252 of actuator 43 to escape at the bottom of pin 42 intothe pumping chamber where the air is on the upper side of the pumpingdiaphragm of the diaphragm pump.

O-rings 52 are provided so that in combination with the quarter turnrelease mechanism of which lugs 262 are a part, the actuator upon aquarter turn thereof is in tight facing connection with the frameportion of the associated pump such that an air tight seal is createdbetween the lower planar surface 276 of actuator lower portion 252 andthe pumping chamber in which the diaphragm resides. Once the air appliedto the diaphragm has pushed the diaphragm downwardly, thereby forcingliquid color below the diaphragm out through the outlet portion of theassociated pump, a strong spring also located in the associated pumppushes the diaphragm upwardly, back into the neutral position, whereuponanother pulse of air, signaled by the microprocessor and released byaction of the solenoid valve, passes downwardly through actuator chamber274 as described above and applies force in the form of air pressure tothe upper side of the pumping diaphragm.

Actuator chamber 274 is sealed such that air cannot enter actuatorchamber 274 other than through the action of microprocessor actuatingthe solenoid valve and providing air in pulses via air inlet 44. Allelectrical connections to potentiometer 36 are provided by potentiometerelectrical leads 268, typical ones of which have been illustrated in thedrawings. These potentiometer electrical leads pass through the polymerfoam body of actuator upper portion 250 and are sealed within thatpolymer foam body so that no air can enter into actuator chamber 274other than the air provided by solenoid valve 70.

While the actuator of the invention has been illustrated in generallycylindrical form, the actuator may be in any other form such as with atriangular horizontal cross-section, a rectangular horizontalcross-section, a hexagonal horizontal cross-section, and an octagonalhorizontal cross-section, etc.

Gasket 254 provides a tight seal between the upper portion 250 and lowerportion 252 of actuator 43. The presence of air pressure within actuatorchamber 274 assures that air will not flow into chamber 274 other thanthrough air inlet 44 as air provided by inlet 44 is on its way to thetop surface of the pumping diaphragm.

1) A method for operating a pump having a movable pumping member and apumping chamber, comprising: a) positioning a movable reciprocablemember in contact with the pumping member to move reciprocally inconcert with the pumping member; b) sensing position of the reciprocablemember and producing signals indicative thereof; c) periodicallyapplying force to the pumping member to move the pumping member andthereby effectuate pumping of fluid from the chamber; d) using thesignals to regulate frequency of force application to the pumping memberto achieve a preselected rate of output from the pump. 2) The method ofclaim 1 further comprising: a) recording the signals at the extremitiesof reciprocable member travel; b) using those signals and known lengthof reciprocable member travel to determine location of the reciproablemember based on signal received at a given time; c) adjusting thefrequency of application of force to the pumping member according to thelocation of the reciprocable member to maintain a desired output fromthe pump. 3) The method of claim 2 wherein the step of using thosesignals and known length of reciprocable member travel to determinelocation of the reciproable member based on signal received at a giventime further includes determining the relationship between duration offorce application to the pumping member and pumping member displacement.4) The method of claim 1 wherein the pumping member is a diaphragm. 5)The method of claim 1 wherein the sensing is performed by apotentiometer. 6) The method of claim 1 wherein the force ispneumatically applied. 7) The method of claim 1 wherein the pumpingchamber is air-tight. 8) The method of claim 5 wherein the potentiometeris within an actuator chamber. 9) The method of claim 8 wherein theactuator chamber is sealed. 10) The method of claim 9 wherein theactuator chamber is within polymer foam. 11) The method of claim 1further comprising adjusting the frequency of application of force tothe pumping member according to the location of the reciprocable memberto maintain a desired output from the pump. 12) The method of claim 2wherein the force is applied to the pumping member by bursts of air. 13)The method of claim 1 further comprising the steps of: a) notingposition of the reciprocable member as indicated by a potentiometersignal; b) applying a burst of air to the pumping member; c) recording asecond potentiometer signal indicative of reciprocable member position;and d) determining pumping member movement as a function of appliedforce duration from the movement of the reciprocable member in responseto the air burst applied to the pumping member. 14) The method of claim1 wherein periodically applying force to the pumping member to move thepumping member and thereby effectuate pumping of fluid from the chamberis performed by controlling duration and timing of air bursts applied tothe pumping member. 15) A method for operating a liquid color diaphragmpump, comprising controlling duration and sequencing of bursts of airapplied to a diaphragm contacting the liquid color being pumped. 16) Amethod for operating a liquid color pump having a movable pumping memberand a sealed pumping chamber, comprising: a) positioning a movablereciprocable member within an actuator chamber in contact with thepumping member to move reciprocally in concert with the pumping member;b) sensing position of the reciprocable member within the actuatorchamber and producing signals indicative thereof; c) periodicallypneumatic applying force to the movable pumping member to move thepumping member and thereby effectuate pumping of liquid color; d) usingthe signals to regulate frequency of pneumatic force application to thepumping member to achieve a desired rate of output from the pump. 17) Anactuator for controlling a movable pumping member in a pump, comprising:a) a housing; b) a movable pin slidably residing within the housing,having an extremity portion passing through the housing for contactingthe movable pumping member and moving unitarily therewith; c) apotentiometer connected to and residing within the housing for sensingmovement of the pin and producing a signal indicative thereof; and d) aspring for biasing the pin against the pumping member. 18) Apparatus ofclaim 17 wherein the housing has a first aperture for connection to asupply of pulsed air, wherein the housing has a sealed chamber withinthe pin, spring and potentiometer reside. 19) Apparatus of claim 17wherein the potentiometer has a movable portion positioned between andcontacting the spring and the pin, for movement with the pin. 20)Apparatus of claim 18 wherein a portion of the housing comprising thechamber is polymer foam. 21) Apparatus of claim 17 wherein the signalsare electrical signals, the potentiometer has terminals providing theelectrical signals indicative of movement of the pin, and the apparatusfurther comprises: a) signal carriers electrically connected to theterminals and passing through housing; and b) electrical connectorsmounted on the housing exterior and being electrically connected to thesignal carriers. 22) Apparatus of claim 20 wherein the signals areelectrical signals, the potentiometer has terminals providing theelectrical signals indicative of movement of the pin, and the apparatusfurther comprises: a) signal carriers electrically connected to theterminals and passing through the polymer foam; and b) electricalconnectors mounted on the chamber exterior and being electricallyconnected to the signal carriers. 23) Apparatus of claim 17 wherein thepumping member is a diaphragm. 24) An actuator for controlling a movablepumping diaphragm in a liquid color diaphragm pump, comprising: a) ahousing; b) a movable pin slidably residing within the housing, havingan extremity portion passing through the housing for contacting themovable pumping member and moving unitarily therewith; c) apotentiometer connected to and residing within the housing for sensingmovement of the pin and producing a signal indicative thereof; and d) aspring for biasing the pin against the pumping member; wherein thehousing comprises a sealed chamber within which the pin, spring andpotentiometer reside; the potentiometer comprises a movable portionpositioned between and contacting the spring and the pin for movementwith the pin; a portion of the housing comprising the chamber is polymerfoam; the potentiometer has terminals providing the signals indicativeof pin movement; and further comprising e) signal carriers electricallyconnected to the terminals and passing through the polymer foam.